How to set up a local spring cloud config server

 Posted on Dec 15, 2015  |  4 minutes

From the official documentation,

Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments.

Steps to configure config server

a. Create a new Gradle project for the config server. In https://start.spring.io/, select the starters for config server.

b. In your project, navigate to src/main/resources. Rename the automatically generated application.properties file to bootstrap.yml.

c. Spring cloud config uses a Git backend by default to lookup property sources, i.e., config files. For this demo application, we will create a git repository on our local file system.

d. Create an empty folder in your file system. Lets name it config-repo. Navigate to this repository via command prompt and execute git init . command. This will create an empty git repository in this folder.

e. We need to provide our config server the location of this git repository. The default strategy for locating property sources is to clone a git repository declared against spring.cloud.config.server.git.uri property. So in our bootstrap.yml, we need to define this property in yaml format like this: 

spring:
  cloud:
    config:
      server:
        git:
          uri: file://(folder path)/config-repo
  
server:
  port: 8003

We can also declare on which port number the config server should run. We have declared that as 8003 above.

f. In your application’s main class add @EnableConfigServer annotation at the class level.

g. When a microservice requests for its property source from a config server, the config server looks up for its property file in following manner. For example, if the name of the requesting service is demo-service and it is running in development profile, then the config server will look for a file with name demo-service-development.yml in the git repository to serve the properties for that service.

h. Currently there are no property files in our git repository. Suppose that we are going to run a microservice named my-service in production mode, we need to create a file named my-service-production.yml in the git repository folder. Remember that simply creating the file in the folder doesn’t add it in the repository. To do that we need to execute following commands: 

git add -A .
git commit -m "some commit message"

i. Lets add a dummy property sample.property in this file that we will use in our microservice. 

sample:
  property: foobar

Steps to configure config client

a. Create another Gradle project. In https://start.spring.io/, select the starters for config client and web.

b. In your project, navigate to src/main/resources. Rename the automatically generated application.properties file to bootstrap.yml.

c. To fetch properties from the config server, we need declare to three things: our service name, the active profile and address of the config server. These tasks can be accomplished by adding following in bootstrap.yml: 

spring:
  application:
    name: my-service
  profiles:
    active: production
  cloud:
    config:
      uri: http://localhost:8003

d. Now, to use the properties in our application we can define a utility class by the name of PropertyUtil inside which we will read the external properties and using this class we can inject those property values wherever required throughout our application.

e. So create a PropertyUtil class in the same package where application’s main class is present, or in a sub-package.

f. The content of the PropertyUtil may be like this: 

@Configuration
@ConfigurationProperties
public class PropertyUtil {
    @Value("${sample.property}")
    private String property;
 
    public String getProperty() {
        return property;
    }
}

@Value injects the external property into the private variable property. Note that @Value cannot be used with static variables.

g. To demonstrate that the external property is fetched correctly, we can set up a rest controller as following: 

@RestController
public class MyServiceController {
    @Autowired
    private PropertyUtil property;
 
    @RequestMapping(value="/", method=RequestMethod.GET)
    public String property() {
        return property.getProperty();
    }
}

h. Now start the config-server application followed by my-service and hit http://localhost:8080 on your browser. Text “foobar” will be displayed.

Java  Microservices 

See also